TY - JOUR
T1 - Cryptic asexual reproduction in <em>Caenorhabditis</em> nematodes revealed by interspecies hybridization
JF - bioRxiv
DO - 10.1101/588152
SP - 588152
AU - Lamelza, Piero
AU - Young, Janet M.
AU - Noble, Luke M.
AU - Isakharov, Arielle
AU - Palanisamy, Meenakshi
AU - Rockman, Matthew V.
AU - Malik, Harmit S.
AU - Ailion, Michael
Y1 - 2019/01/01
UR - http://biorxiv.org/content/early/2019/03/26/588152.abstract
N2 - Most animal species reproduce by sex. Theory predicts there are advantages to being able to switch reproduction between sexual and asexual modes. However, facultative sex is rarely observed in animals, implying that there are strong selective pressures that prevent asexuality arising from an obligately sexual ancestor. One of the critical steps in the evolution of asexuality from a sexual ancestor is the transition from haploid to diploid maternal inheritance. Here we report that interspecific hybridization between two sexual Caenorhabditis nematode species (C. nouraguensis females and C. becei males) results in two classes of viable offspring. The first class consists of fertile offspring, which are produced asexually by sperm-dependent parthenogenesis (also called gynogenesis or pseudogamy); these progeny inherit a diploid maternal genome but fail to inherit a paternal genome. The second class consists of sterile hybrid offspring, which inherit both a diploid maternal genome and a haploid paternal genome. Using whole-genome sequencing of individual viable worms, we show that diploid maternal inheritance in both asexually produced and hybrid offspring results from the inheritance of two randomly selected homologous chromatids from C. nouraguensis oocytes. This genetic mechanism of diploid maternal inheritance is indistinguishable from that of many obligately asexual species. Furthermore, we show that intraspecies C. nouraguensis crosses can also result in a low frequency of asexual reproduction through diploid maternal inheritance. Thus, C. nouraguensis provides a genetically tractable model to study the evolutionary origins of asexuality from obligately sexual species.
ER -